A human exposure experiment with house dust is used to illustrate how exposure experiments can be used as an IAQ research tool. New health information in relation to suspended particulate matter is presented. Results of human exposure experiments using formaldehyde and volatile organic compounds (VOCs) are then used to show how climate chamber experiments have been used in risk evaluations and in emission tests for source and risk identification. The presentation shows that controlled experiments and epidemiological investigations both in the field and in the laboratory are needed as research tools in IAQ sciences. Based on the formaldehyde and VOC cases typical phases of an environmental pollution case are identified. Different subgroups of researchers with different aims, training, research tools, and end users of their results are associated with these phases. A successful national public health program calls for research contributions from all these groups.  (For more information please visit the Univeristy of Aarhus website at : www.mil.au.dk/lm)